A cat or felines upper respiratory infection is caused by a Viral bacteria.
The most common viruses that cause cats upper respiratory infections are Feline Herpesvirus Type-1 (also known as feline viral rhinotracheitis or FVR) and Feline Calicivirus (FCV), while the most common bacteria that cause upper respiratory infections in cats are Bordetella bronchiseptica (B. bronchiseptica) and Chlamydophila felis (C. felis).
The virus is spread from cat to cat but Humans cannot catch the upper respiratory virus from their cats.